I don't know if would ever wait to offer it to somebody else, especially if the person was just asking for a price.
I think I would message both people letting them know that others are interested, user A has first dibs, but they need to let you know within the next day (or longer if you see fit) or you will move to the next in line.
I now try to post pics of any ball that I am selling, and I try to take at least 4 so that all sides can be viewed. It's easier to just take pics and post them than to have to send individual e-mails.
But, I've pretty much seen all the stated behavior. One time I must have sent 12 different pictures because the person kept asking "is that a scratch or flash/lighting a few inches above the pin? Can you send me a better picture?" "Thanks, but I still can't tell, can you zoom in closer?"
Heck, I've even sold a few times where the buyer didn't bother to let me know they received the items.
If ebay and paypal didn't take 10-16% of the final value I'd probably sell there, but it really isn't any better with the questions and responses.